PeCMan is a web application maintaining a list of web objects (data) in the form of URLs (references) with user-provided tags (information). These tags are then used to allow the original contributor (principal user) of the information to (re-)find the references and data, or to share the information and data with others (participant users). These participants can be friends, family, or generally groups of people. The operating model of PeCMan is that PeCMan only maintains the references and tags, and that the referred to objects themselves are retrieved by an application executing on the user's host. Thus the procedure for a participant user is to enter a few tags to PeCMan, PeCMan matches the tags to its information and returns the references to the user, whereupon the user will try to obtain the referred to data.
The PeCMan method for obtaining information from the web works well for publicly available data but fails for private shared data. Private shared data are references to objects that are stored behind, e.g. a password protected web-site. In this case, a user needs to login into the web service offering the referred to data. This is reasonably straightforward if the owner of the referred to data is the same user that is looking for the data. However, sharing private data with participants is a challenge and can only be realized if the principal owner of the data can provide the participant with the credentials for the service. According to the prior art, to support private non-shared and shared content, the principal PeCMan server typically stores the user credentials with the URL that is being pointed at. If private content is being addressed, a participant PeCMan client sets up a communication channel to a PeCMan server, which then establishes a connection to the storage provider on behalf of the participant PeCMan client, i.e. the PeCMan server acts as proxy for the participant PeCMan client. The downside of this method of data sharing in PeCMan is that all private data are transmitted through the PeCMan proxy. This means that PeCMan can become a bottleneck for accessing private content.